Electronic component comprising predominantly organic functional materials and a method for the production thereof

ABSTRACT

Electronic component comprising predominantly organic functional materials and a process for the production thereof. The invention concerns an electronic component comprising predominantly organic functional materials with improved through-plating. The through-plating is formed in the present case prior to application of the insulating layer, in the form of a free-standing raised portion.

Electronic component comprising predominantly organic functional materials and a process for the production thereof

The invention concerns an electronic component comprising predominantly organic functional materials with improved through-plating.

Components are known for example from GR 2001 P03239; 2001 P20024 in so-called ‘polymer electronics’. This means the new electronics which are not based on the traditionally known silicon-based conducting materials and which consist of substantially organic materials, in particular layers of organic plastic materials. The system for producing through-platings (vias formation) for polymer electronics permits conductive connections to be made between layers in different levels of components. In that situation a through-plating passes through one or more insulating or semiconductor intermediate layers, that is to say so-called ‘central functional layers’. Those through-platings are essential for the production of logic-capable integrated circuits. They can be produced both with a printing procedure and also in conventional manner by means of optical lithography. When using a printing process, that process step can be integrated into mass production, which is essential in particular in the production of low-cost articles.

In the production of such electronic components the predominantly organic material is applied by way of thin film processes. Because the thin films have a high level of sensitivity in relation to mechanical stress and/or chemical solvents, high demands are made on the processes for forming the through-platings. It will be appreciated that those high demands are reflected in the production costs. Hitherto through-platings have been produced on the finished thin layers, in which case the risk of the thin layers being damaged weighs very heavily because the functionality of the entire component is brought into question as soon as one of the functional layers is damaged.

Therefore an object of the invention is to provide a mass production-compatible process for the production of at least one through-plating, which takes account of the properties of the delicate thin layers of organic material. Another object of the invention is to provide an electronic component which has at least one through-plating which was applied prior to the insulating layer.

The subject of the invention is therefore an electronic component with predominantly organic functional layers, which as at least one through-plating whose cross-sectional profile is so characteristic that it can be seen thereon that at least one lower layer was locally treated prior to the application of at least one central functional layer. The subject of the invention is also a process for the production of at least one through-plating of an electronic component comprising predominantly organic material, wherein the through-plating is formed prior to the application of the insulating layer.

Hitherto vias have always been formed by a procedure whereby holes are subsequently produced in existing layers by drilling, etching away or usual methods involving non-cross-linking such as lithography and so forth, the holes then being filled with conducting material to form the through-plating. That mostly involves a uniform cross-section in respect of the through-plating formed, and that cross-section can be characteristically and easily recognized on the finished product by means of a cross-sectional profile.

The method proposed herein for the first time, for applying the through-plating (VIAS) on the substrate, the conducting and/or semiconducting layer, at any event prior to the layer which is to be through-plated and which therefore is generally insulating, provides through-platings which at least in accordance with some embodiments are of a cross-sectional profile which tapers from below upwardly, comparable to a truncated cone. The contours of the vias are generally also of a shape which is typical of the kind of manufacture, for example printing. The subsequent layer which are to be through-plated are substantially adapted around the vias to that shape. The contour shape is not sharply drawn and/or even of a serrated configuration for example in accordance with an embodiment—considered microscopically—, whereas the contours of the conventional vias which can be obtained by subsequent drilling generally have sharp contours.

In accordance with an embodiment the vias are formed in the configuration of free-standing raised portions. Through-plating in that case is effected only with the application of the thin and/or insulating layer. It is advantageous if the surface of the vias is rough for later contact with the upper conductor. If the insulating layer or layers involves a thin film or films, the through-platings are produced in succession automatically because the film of organic material breaks open at the through-plating points, even if the raised portion is not high by the entire thickness of the layer. The holes produced in that way in the insulating film can produce an electrical connection between the various levels of an electronic component. In that respect, either the holes can be only subsequently filled with a conductive material, or the through-platings which have been first applied are already conductive.

In the situation which does not involve a thin film which automatically breaks open, a break-through can be achieved at the through-plating locations by specifically targeted mechanical treatment.

At any event however in accordance with the invention the vias are applied prior to the central functional layer, that is to say generally an insulating layer, and the delicate, preferably structured layers remain spared by the through-plating process.

The term ‘organic material’ or ‘functional material’ or ‘(functional) polymer’ includes here all kinds of organic, metallorganic and/or organic-inorganic plastic materials (hybrids), in particular those which are identified in English for example by ‘plastics’. This involves all kinds of substances with the exception of the semiconductors which form the conventional transistors (germanium, silicon) and the typical metallic conductors. Restriction in a dogmatic sense to organic material as carbon-bearing material is accordingly not intended, but rather the broad use of for example silicones is also envisaged. In addition the term is not to be subjected to any restriction in regard to the molecule size, in particular to polymeric and/or oligomeric materials, but the use of small molecules is certainly also possible. The word component ‘polymer’ in the expression functional polymer is historically governed and in that respect does not make any statement about the presence of an actually polymeric bond.

Embodiments of the Invention are also described in greater detail hereinafter with reference to Figures showing cross-sectional profiles by way of example on an enlarged scale for the sake of improved clarity.

FIG. 1 shows a carrier substrate (for example a PET film) indicated at 1 with the corresponding lower conductor tracks 2 (for example gold, polyaniline, PEDOT, carbon black, graphite and conducting silver).

FIG. 2 shows, in relation to the structure of FIG. 1, the free-standing through-plating 3 which is applied on a lower conductor track and/or layer 2. The through-plating 3 is applied for example by a printing procedure or lithographically. Any desired manner of manufacture which produces such a through-plating 3 on a lower layer 2 can be envisaged. The through-plating 3 comprises for example polyaniline, PEDOT, carbon black, graphite or conducting silver. It can however be provided of another conducting or non-conducting material. The shape of that through-plating 3 can be for example tower-shaped of a configuration which is tapered upwardly. The surface can have a certain degree of roughness, which promotes later contacting. As the substrate 1 and the conductor track or tracks 2 generally enjoy a high level of mechanical stability, a mass production process can be used without any problem for making the through-plating 3.

FIG. 3 again shows the same structure in another stage in the process, where two further layers 4 and 5 which can comprise semiconducting or insulating material have already been applied. The following for example can be used as semiconductor: polyalkithiophene or polyfluorene, while the insulator used can be for example polyhydroxystyrene, polymethylmethacrylate or polystyrene. By virtue of its size and/or its nature the through-plating 3 passes through the two central functional layers 4, 5 and thus forms the desired contact.

FIG. 4 shows the upper conductor track 6 on the structure known from the other Figures, and it can be seen that the through-plating 3 affords a conducting connection between the lower conductor track 2 and the upper conductor track 6.

FIG. 5 shows the same layer structure as that shown in FIGS. 1-3, except that in FIG. 5 the two functional layers 4, 5 are restricted to one layer 4.

FIG. 6 shows two such structures as shown in FIG. 5, wherein one structure is turned through 180° so that the respective through-platings 3 are in mutually opposite relationship.

In FIG. 7 the two structures have been brought into contact with each other, as occurs for example in a lamination process. As a result both the respective functional layers 4, 5 and the respective vias form a unit and produce the defined electrical connection. The shape of the through-plating 3 which results in that case and which can be recognized in the cross-sectional profile is here a hyperboloid, that is to say the shape of two truncated cones which are joined ‘head-to-head’.

FIG. 8 shows another way of producing the through-plating. A defined disruption location 7 has been applied to the lower conductor track 2. The location 7 can comprise both conductive and also insulating material. In addition the disruption location 7 can be produced by a local chemical or physical treatment. The through-plating 3 is shaped by tearing open the functional layer or layers 4 at the disruption location 7 and subsequently filling the region around the disruption location 7 with conductive material of the upper conductor track 6.

The disruption location 7 provides that, around it, the subsequently applied central functional layer or layers 4, 5 tears or tear open and/or is or are absent due to non-wetting or in some other fashion, so that a region is produced around the disruption location 7, in which the lower layer 2 to be contacted is exposed, in the operation of forming the upper layer 6 to be contacted.

The contacting of the conducting layer 2 to the conducting layer 6 functions by virtue of the exposed region on the layer 2 being larger than the disruption location 7. For that reason the disruption location 7 can comprise both conducting and also insulating material.

The through-plating 3 is therefore produced in such a way that, upon application of the semiconductor and insulator layer, the lower conductor layer 2 in FIG. 1 is locally not wetted. In other words, at the location of the vias, holes are deliberately produced in the layers which are to be through-plated. The actual through-plating 3 is then afforded by filling those holes with conductive material of the upper conductor track 6. That is effected for example automatically when applying the gate level.

The local non-wetting can also occur in such a way that a disruption is deliberately produced there, at which the film tears open and thus forms a hole. The disruption can be a material applied—by printing—, in which respect the natural shape of the material (particles) or the shape produced (point) promotes the process of tearing open the film. A further possibility for local non-wetting provides that there the physical/chemical properties of the surface are altered. The altered physical/chemical properties can be for example an increased level of surface energy, whereby from the outset no wetting of that location occurs, which again results in the same effect, namely hole formation. The increased level of surface energy is possible for example by applying by printing a chemical solution (solvent, acid, base, a reactive compound) and subsequent removal and/or independent evaporation.

A physical (local) treatment of the lower functional layer can be effected for example by roughening up, laser irradiation, plasma treatment (for example corona), UV irradiation, IR irradiation and/or thermal treatment.

It is also possible locally to apply for example a material (lacquer, wax . . . ) which has non-wetting properties or which prevents wetting (comparable to the foregoing disruption locations). The material can be removed again prior to or after application of the intermediate layers, wherein at the location of the through-plating there is a hole in the cover layer, and that hole is then filed with the conductive upper layer.

In the embodiment of the through-plating in the form of a raised portion with a conductive or non-conductive material, it is possible both for the tip of the raised portion to ‘pierce’ through the functional layer and also for it to be shorter than the thickness of the functional layer, that is to say a simple raised portion which does not pass through the functional layer. In any case in the gate electrode printing process which follows the formation of the vias the conducting components (lower and upper layer/conductor track 2 and 6) are brought into contact by pressure because the intermediate layers 4, 5 are comparatively thin.

With the fast processing speeds of a mass production process, mechanical stressing of the material being printed upon is extremely critical and as far as possible should be avoided. Direct processing of the insulating layer would cause uncontrollable defect locations. The possibility described herein for producing the vias for the first time permits integration of the through-plating operation in a mass production process. 

1. An electronic component comprising a Plurality of predominantly organic functional layers at least one of which layers is a lower layer and at least one other of the layers is a central layer, said layers being coupled to at least one through-plating, having a cross-sectional profile which extends through the layers transversely to the layers and which through plating extends at least in part below the at least one central functional layer, has non-sharp contours and/or is at least in part in the shape of a truncated cone, whereby prior to the application of the through plating to the at least one central functional layer the at least one lower functional layer is locally treated with the through plating.
 2. The An electronic component as set forth in claim 1 wherein the cross-sectional profile of the through plating comprises a free-standing raised portion of electrically conductive or non-conductive material.
 3. The electronic component as set forth in claim 2 wherein the conductive material includes polyaniline, pedot, carbon black, graphite, conducting silver and/or metal and/or a mixture thereof.
 4. The electronic component as set forth in claim 2 including a non-conducting material wherein at least one of the central functional layer and the non-conducting material includes an insulating material such as polyhydroxystyrene, polymethylmethacrylate and/or polystyrene and/or a semiconducting material such as polyalkylthiophene and/or polyfluorene and/or a mixture thereof.
 5. The electronic component as set forth in claim 1 wherein of the through-plating is in the form of a raised portion that has a surface roughness which promotes contacting.
 6. The electronic component as set forth in one of the preceding claims wherein the cross-sectional profile shows a chemical treatment at least of a lower functional layer.
 7. The electronic component as set forth in one claims 1-5 wherein the cross-sectional profile shows a physical treatment of at least of a lower functional layer.
 8. The electronic component as set forth in one of claims 1-5 wherein the cross-sectional profile shows a local disruption location on the at least one lower functional layer.
 9. The electronic component as set forth in one of claims 1-5 wherein the cross-sectional profile shows a preceding locally restricted change in the surface energy of the at least one lower functional layer, at which no wetting by a subsequently applied organic material of a subsequent central functional layer occurred.
 10. The electronic component as set forth in one of claims 1-5 wherein a disruption location is produced locally on the at least one lower functional layer chemically by application of a material, at which prior to or after application of one of the central functional layers the dislocation can be detected by at least one of material residues, the shape of the disruption location and/or traces on the at least one lower functional layer.
 11. The electronic component as set forth in one of claims 1-5 wherein the component is made up of a plastic substrate which includes one of the following materials: PET, PP, PEN, polyimide, polyamide and/or coated paper.
 12. A process for the production of at least one through-plating of an electronic component comprising predominantly organic material and an insulating layer, wherein the through-plating is formed prior to application of the insulating layer.
 13. The use of the component as set forth in one of claims 1 through 5 in an electronic product. 